Illuminating device

ABSTRACT

To a constant-current power supply whose output current can be variably set, light emitting modules can be connected in parallel. A control unit recognizes connection information outputted from an information output unit provided in each of the light emitting modules and varies the output current of the constant-current power supply. Drive can be controlled in response to a state of the connected light emitting modules such as the connecting number of light emitting modules.

INCORPORATION BY REFERENCE

The present application claims priority under 35 U.S.C. §119 to JapanesePatent Application No. 2007-145326 filed on May 31, 2007. The content ofthe application is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an illuminating device for which lightemitting modules each including either one light source or a pluralityof light sources connected in series can be connected in parallel witheach other.

BACKGROUND OF THE INVENTION

Conventionally, as disclosed in, for example, Japanese Laid-Open PatentPublication No. 11-68161, Japanese Laid-Open Patent Publication No.2002-8409, Japanese Laid-Open Patent Publication No. 2007-27316, andJapanese Laid-Open Patent Publication No. 2007-96287, etc., there is anilluminating device for which a plurality of LED modules being lightemitting modules for each of which a plurality of light emitting diodes(LEDs) are connected in series can be connected as light sources inparallel to a power supply. In such an illuminating device, in order tolight the LEDs of each light emitting module almost uniformly, the powersupply is provided as a constant-current power supply to supply aconstant current to the light emitting module.

However, in the above-described illuminating device, since the powersupply is provided as a constant-current power supply, this is effectivewhen the connecting number of LED modules is preset, while in such acase where the connecting number of LED modules is arbitrarily increasedor decreased, there is a problem that drive cannot be controlled inresponse to a state of the connected LED modules, such that current tobe supplied to each LED module is insufficient or excessive, and theLEDs cannot be lit in a desired state.

The present invention has been made in view of such a problem, and anobject thereof is to provide an illuminating device whose drive can becontrolled in response to a state of the connected light emittingmodules.

SUMMARY OF THE INVENTION

The present invention includes: a constant-current power supply whoseoutput current can be variably set; alight emitting module includingpaired main terminals that can be connected to this constant-currentpower supply and one or more light sources connected between thesepaired main terminals; an information output unit that is provided inthis light emitting module and that outputs connection information ofthis light emitting module; and a control unit that recognizes theconnection information outputted from this information output unit andvaries the output current of the constant-current power supply.

The light source is preferably, for example, an LED but is not limitedto an LED.

The light emitting module is, for example, a unit for which one or morelight sources are disposed with a predetermined arrangement.

The information output unit is, for example, a resistor, amicrocomputer, or the like, which outputs a connecting state of eachindividual light emitting module.

The control unit is, for example, a microcomputer, or the like providedin the constant-current power supply.

And, as a result of the control unit recognizing the connectioninformation outputted from the information output unit provided in eachof the light emitting modules and varying the output current of theconstant power supply, drive can be controlled in response to a state ofthe connected light emitting modules, for example, the connecting numberof light emitting modules.

Moreover, in the present invention, the information output unit outputsthe connection information by at least either of the main terminals ofthe light emitting module.

And, as a result of using at least either of the main terminals of thelight emitting module also for output of the information output unit,the configuration can be simplified in comparison with when a terminalfor outputting information or the like is separately provided.

Moreover, in the present invention, the information output unit includesa resistor connected between the main terminals of the light emittingmodule, and the control unit recognizes a current that flows to theresistor when a voltage given between the main terminals by theconstant-current power supply is lower than a voltage at which the lightsource emits light in a predetermined state as the connectioninformation of the light emitting module.

And, as a result of the control unit recognizing a current that flows tothe resistor when a voltage between the main terminals is lower than avoltage at which the light source emits light in a predetermined stateas the connection information of the light emitting module, the mainterminal of the light emitting module can be easily used also as theinformation output unit.

Moreover, in the present invention, timing where the control unitrecognizes the connection information of the light emitting module is atstart-up before the light source is lit.

And, as a result of the control unit recognizing the connectioninformation of the light emitting module at start-up before the lightsource is lit, no time for recognizing the connection information of thelight emitting module is separately required, so that usability isimproved.

Moreover, in the present invention, the information output unit includesa resistor connected between the main terminals of the light emittingmodule, the constant-current power supply controls the output current byPWM control, and the control unit recognizes a current that flows to theresistor due to a voltage generated in an OFF period of the PWM controlof the constant-current power supply between the main terminals of thelight emitting module as the connection information of the lightemitting module.

And, as a result of the control unit recognizing a current that flows tothe resistor due to a voltage generated in an OFF period of the PWMcontrol of the constant-current power supply as the connectioninformation of the light emitting module, the main terminal of the lightemitting module can be easily used also as the information output unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of an illuminating device showing a firstembodiment of the present invention,

FIG. 2 is a circuit diagram of an illuminating device showing a secondembodiment of the present invention,

FIG. 3 is a circuit diagram of an illuminating device showing a thirdembodiment of the present invention,

FIG. 4 is a graph showing an output voltage of a constant-current powersupply of the illuminating device,

FIG. 5 is a circuit diagram of an illuminating device showing a fourthembodiment of the present invention,

FIG. 6 is a graph showing electrical characteristics of a light sourceof the illuminating device,

FIG. 7 is a graph showing operation of the illuminating device, and

FIG. 8 is a graph showing an output voltage of a constant-current powersupply of an illuminating device of a fifth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

A first embodiment is shown in FIG. 1, and FIG. 1 is a circuit diagramof an illuminating device.

As shown in FIG. 1, for an LED lighting device 11 being an illuminatingdevice, connected to a constant-current power supply 12 is one or aplurality of light emitting modules 13 in parallel with each other.

The constant-current power supply 12 is connected to a commercialalternating current power supply “e” via a diode bridge DB being arectifying unit. Moreover, this constant-current power supply 12 hasoutput terminals 12 a and 12 b connected to main terminals 13 a and 13 bof the light emitting module 13, respectively, and an input terminal 12c to which connection information outputted from the respective lightemitting modules 13 are inputted and has, between the output terminals12 a and 12 b, for example, a semi-fixed variable constant-currentsource 15 whose output current I_(L) can be variably set.

A control unit 16 of this is, for example, a microcomputer or the like,which is connected to the input terminal 12 c to recognize theconnection information from the respective light emitting modules 13 andset an output current from the variable constant-current source 15(constant-current power supply 12). Moreover, between this control unit16 and the input terminal 12 c, a direct-current power supply 17 being aconstant-voltage source is connected via a resistor 18.

For each light emitting module 13, between the main terminals 13 a and13 b, a resistor 21, a transistor 22 serving as a switching element, andone or a plurality of LEDs 23 being a light source or light sources areconnected in series to each other, and an information output resistor 24for outputting connection information is connected between the LED 23and the main terminal 13 b, and this information output resistor 24 isconnected to an information output terminal 13 c.

The transistor 22 is, for example, a PNP-type bipolar transistor, whoseemitter being an output terminal is connected to the resistor 21,whereby an emitter potential is set, and whose collector being an inputterminal is connected to the LED 23. Moreover, in the transistor 22 ofthe first light emitting module 13 connected to the constant-currentpower supply 12, the emitter is connected to the base being a controlterminal. And, the bases of the transistors 22 of the respective lightemitting modules 13 are connected to each other via an output terminal13 d of the light emitting module 13, and base potentials of thetransistors 22 of the respective light emitting modules 13 are set tothe same potential as each other. Accordingly, these transistors 22 forma leveling circuit, so that lighting currents of the LEDs 23 that flowto all light emitting modules 13 become the same current.

The respective information output resistors 24 are set to almost equalresistances to each other, and connected in parallel with each otherbetween the information output terminals 13 c. Accordingly, theserespective information output resistors 24 are connected to thedirect-current power supply 17 in parallel with each other. And, theinformation output resistors 24 and the information output terminals 13c form information output units 26.

Next, operations of the present embodiment will be described.

When a predetermined output current I_(L) is outputted between theoutput terminals 12 a and 12 b from the variable constant-current source15 of the constant-current power supply 12, lighting currents flow tothe respective light emitting modules 13 connected in parallel to theconstant-current power supply 12 and the respective LEDs 23 emit light.

At this time, the lighting currents of the respective light emittingmodules 13 are set almost equal to each other by a leveling effect ofthe respective transistors 22. That is, the lighting currents of therespective light emitting modules 13 are equal to currents obtained byequally dividing the output current I_(L) by the number of lightemitting modules 13, so that the LEDs 23 of the respective lightemitting modules 13 emit light almost uniformly.

On the other hand, in the constant-current power supply 12, since thenumber of information output resistors 24 to be connected in parallel tothe direct-current power supply 17 differs depending on the number ofconnected light emitting modules 13, potential at a position between theresistor 18 and the input terminal 12 c connected to the control unit 16is changed. More specifically, when the connecting number of the lightemitting modules 13 is increased or decreased, the number of informationoutput resistors 24 connected in parallel with each other is increasedor decreased, and thus all resistances on the side of these informationoutput resistors 24 are decreased or increased in inverse proportion,and potential at a position between the resistor 18 and the inputterminal 12 c is lowered or raised.

Then, the control unit 16 reads this potential to thereby recognize theconnection information of the light emitting modules 13, here, theconnecting number, and thus, in response to this recognized connectingnumber, the output current I_(L) to be supplied from the variableconstant-current source 15 is varied.

As such, the control unit 16 varies the output current I_(L) of theconstant-current power supply 12 in response to connection informationoutputted from the information output unit 26 provided in each of thelight emitting modules 13, here, the connecting number of light emittingmodules 13, whereby drive of the LED lighting device 11 can becontrolled in response to a state of the connected light emittingmodules 13.

Moreover, by forming the information output unit 26 of the informationoutput resistor 24 and the information output terminal 13 c, theinformation output unit 26 can be easily formed in each light emittingmodule 13, whereby complication of the configuration of the lightemitting module 13 can be prevented.

Next, a second embodiment is shown in FIG. 2, and FIG. 2 is a circuitdiagram of an illuminating device. Also, the same configurations andoperations as those of the abovementioned first embodiment will bedenoted with identical reference numerals, and descriptions thereof willbe omitted.

In the second embodiment, in place of the information output resistors24 of the respective light emitting modules 13 of the abovementionedfirst embodiment, microcomputers 31 which are storing units serving asinformation units are connected via power supply circuits 32,respectively, whereby the information output units 26 are formed.

Each microcomputer 31 detects an abnormality of the LED 23 of the lightemitting module 13 and the like via a load abnormality detecting unit34. And, each microcomputer 31 stores, as connection information of thelight emitting modules 13, specifications and the number of the lightemitting modules 13, the accumulated lighting time in the light emittingmodule 13, load abnormality information outputted from the loadabnormality detecting unit 34, and the like in a built-in unillustratedmemory or the like.

Moreover, the power supply circuit 32, which supplies power to themicrocomputer 31, has a transistor 35 connected, to the main terminal 13a, in parallel with the resistor 21 and a Zener diode 36 and a capacitor37 connected to the transistor 35.

The transistor 35 is, for example, an NPN type bipolar transistor, whosecollector is connected in parallel with the resistor 21, whose base isconnected to a cathode side of the Zener diode 36, and whose emitter isconnected to a plus side of the capacitor 37.

The Zener diode 36 sets a base potential of the transistor 35, an anodeside thereof is grounded via the main terminal 13 b.

The capacitor 37, which charges electricity to be supplied to eachmicrocomputer 31, is, for example, a large-capacity capacitor such as anelectrolytic capacitor, and a plus side and a minus side thereof areconnected to the microcomputer 31, respectively, and the minus side isgrounded via the main terminal 13 b.

And, in each light emitting module 13, most of the lighting currentsupplied from the constant-current power supply 12 flows to the LED 23via the resistor 21 and the transistor 22, and by a leveling effect ofthe resistors 21 and the transistors 22, the LEDs 23 are lit almostuniformly in all light emitting modules 13. Simultaneously, part of thelighting current is charged in the capacitor 37 by an effect of thetransistor 35 so that power is supplied to the microcomputer 31, andvarious types of connection information are outputted from thismicrocomputer 31 to the control unit 16. Also, the capacitor 37 can becharged up to a voltage almost equal to a breakdown voltage of the Zenerdiode 36.

Furthermore, in the control unit 16, operation of the constant-currentpower supply 12 is controlled based on the connection informationoutputted from the microcomputers 31 of the respective light emittingmodules 13, whereby drive of the LED lighting device 11 is controlled.

More specifically, the control unit 16 can control drive of the LEDlighting device 11 in response to a state of the connected lightemitting modules 13 by, for example, increasing or decreasing the outputcurrent I_(L) to be supplied from the variable constant-current source15 according to the specifications and the number of the light emittingmodules 13 outputted from the microcomputer 31, stopping drive of theLED lighting device 11 when the accumulated lighting time of the lightemitting module 13 outputted from the microcomputer 31 is larger than apredetermined time previously set, and performing a protectiveoperation, such as limiting the output current I_(L) or stopping driveof the LED lighting device 11, when a load abnormality such as, forexample, opening or short-circuiting of the LED 23 has occurred as loadabnormality information outputted from the microcomputer 31.

Moreover, the information output 26 including the microcomputer 31allows storing various connection information of the light emittingmodules 13 in the microcomputer 31, and thus in response to theseconnection information, drive of the light emitting module 13 can bevariously controlled.

Next, a third embodiment is shown in FIG. 3 and FIG. 4, wherein FIG. 3is a circuit diagram of an illuminating device, and FIG. 4 is a graphshowing an output voltage of a constant-current power supply of theilluminating device. Also, the same configurations and operations asthose of the abovementioned second embodiment will be denoted withidentical reference numerals, and descriptions thereof will be omitted.

For the third embodiment, a parallel circuit of a resistor 41 and atransistor 42 serving as an information unit is connected between theLED 23 and the main terminal 13 b in the abovementioned embodiment.

The transistor 42 is, for example, an NPN-type bipolar transistor, whosecollector is connected to the LED 23 side and whose emitter is groundedvia the main terminal 13 b, and the resistor 41 is connected between thecollector and emitter. Moreover, between the base and emitter of thetransistor 42 of the first light emitting module 13 connected to theconstant current power supply 12, a pulse power supply 43 is connected,and the resistor 41, the transistor 42, and the pulse power supply 43form the information output unit 26. And, the pulse power supply 43 isconnected via a connection terminal 13 e to the bases of the transistors42 of all other light emitting modules 13.

Moreover, in the constant-current power supply 12, provided is an outputvoltage detecting unit 45 that detects an output voltage Vout betweenthe output terminals 12 a and 12 b and a load fitting statediscriminating unit 46 that discriminates a state of the light emittingmodule 13 based on the output voltage Vout and the like detected by theoutput voltage detecting unit 45, and the output voltage detecting unit45 and the load fitting state discriminating unit 46 form the controlunit 16.

And, in each light emitting module 13, the lighting current suppliedfrom the constant-current power supply 12 flows to the LED 23 via theresistor 21 and the transistor 22, and by a leveling effect of theresistors 21 and the transistors 22, the LEDs 23 are lit almostuniformly in all light emitting modules 13.

Furthermore, in the information output unit 26, as a result of a pulsevoltage being applied between the base and emitter of the transistor 42at a duty ratio or a frequency set for each type of the light emittingmodule 13 from the pulse power supply 43, this transistor 42 repeatsturning on and off in predetermined periods, so that a potentialdifference (collector-emitter voltage of the transistor 42) between bothends of the resistor 41 is periodically reduced. Therefore, the voltagebetween the main terminals 13 a and 13 b of the light emitting module13, that is, the output voltage Vout of the constant-current powersupply 12 is periodically reduced by, for example, a voltage Va, asshown in FIG. 4.

Accordingly, as a result of the output voltage detecting unit 45detecting a frequency of increases/decreases in the output voltage Vout,the load fitting state discriminating unit 46 detects the type of theconnected light emitting module 13, and in response to the type of thelight emitting module 13 thus detected, the load fitting statediscriminating unit 46 sets the output current I_(L) from the variableconstant-current source 15.

Moreover, when the connecting number of light-emitting modules 13 isincreased, a supply current to each transistor 42 connected in parallelto the pulse power supply 43 is decreased, whereby a potentialdifference between both ends of the resistor 41 of each light emittingmodule 13 is decreased in inverse proportion, so that the voltage Va inthe output voltage Vout of the constant-current power supply 12 isincreased.

Accordingly, as a result of detecting the size of this voltage Va, thatis, the amplitude of the output voltage Vout by the output voltagedetecting unit 45, it becomes possible for the load fitting statediscriminating unit 46 to detect the connecting number of the lightemitting modules 13, and in response to the connecting number of thelight emitting modules 13 thus detected, the load fitting statediscriminating unit 46 sets the output current I_(L) from the variableconstant-current source 15.

As such, according to the abovementioned third embodiment, the controlunit 16 varies the output current I_(L) of the constant-current powersupply 12 in response to the connection information outputted from theinformation output unit 26 provided in each of the light emittingmodules 13, here, the type or the connecting number of light emittingmodules 13, drive of the LED lighting device 11 can be controlled inresponse to a state of the connected light emitting modules 13.

Moreover, for the information output unit 26, by using the mainterminals 13 a and 13 b that supply electricity from theconstant-current power supply 12 also for outputting the connectioninformation, the configuration can be simplified in comparison with thatwhen information outputting terminals or the like are separatelyprovided.

Next, a fourth embodiment is shown in FIG. 5 to FIG. 7, wherein FIG. 5is a circuit diagram of an illuminating device, FIG. 6 is a graphshowing electrical characteristics of a light source of the illuminatingdevice, and FIG. 7 is a graph showing operation of the illuminatingdevice. Also, the same configurations and operations as those of theabovementioned respective embodiments will be denoted with identicalreference numerals, and descriptions thereof will be omitted.

For the fourth embodiment, the light emitting module 13 is formed with aseries circuit of the LED 23, a transistor 51, and a resistor 52 betweenthe main terminals 13 a and 31 b, and to this series circuit, aninformation output resistor 53 which is a resistor serving as aninformation unit is connected in parallel.

The transistor 51 is, for example, an NPN-type bipolar transistor, whosecollector is connected to the LED 23 and whose emitter is connected tothe resistor 52, and an emitter potential is set by this resistor 52.Moreover, in the transistor 51 of the first light emitting module 13connected to the constant-current power supply 12, the collector isconnected to the base. And, the bases of the transistors 51 of therespective light emitting modules 13 are connected to each other via anoutput terminal 13 f of the light emitting module 13, and basepotentials of the transistors 51 of the respective light emittingmodules 13 are set to the same potential as each other. Accordingly,these transistors 51 form a leveling circuit, so that lighting currentsof the LEDs 23 that flow to all light emitting modules 13 become thesame current.

The information output resistor 53 is set to a sufficiently greatresistance in comparison with that on the LED 23 side so that, at thetime of operation of the light emitting module 13, the lighting currentthat flows to the LED 23 and the like can be secured.

And, the control unit 16 detects the connection information of the lightemitting modules 13, here, the connecting number of the light emittingmodules 13 by a current that flows through the information outputresistor 53, from start-up of the LED lighting device 11, while theoutput voltage Vout supplied from the constant-current power supply 12is a voltage “a” less than a lighting voltage “b” of the LED 23 shown inFIG. 6, that is, in a period up to a time T1 shown in FIG. 7.

More specifically, as a result of the number of the information outputresistors 53 connected in parallel to the constant-current power supply12 being increased or decreased due to an increase or decrease in theconnecting number of the light emitting modules 13, the current value tobe recognized by the control unit 16 is increased in proportion to theconnecting number, so that by reading this current value, the controlunit 16 detects the connecting number of the light emitting modules 13.

And, in the control unit 16, the output current I_(L) from the variableconstant-current source 15 of the constant-current power supply 12 isset in response to the connecting number of the light emitting modules13 thus recognized, whereby drive of the LED lighting device 11 iscontrolled.

Thereafter, in the respective light emitting modules 13, the respectiveLEDs 23 are lit when the output voltage Vout supplied from theconstant-current power supply 12 has reached the lighting voltage “b,”and lighting of these LEDs 23 is unified in all light emitting modules13 by a leveling effect of the resistors 52 and the transistors 51.

More specifically, the control unit 16 varies the output current I_(L)of the constant-current power supply 12 in response to connectioninformation outputted from the information output unit 26 provided ineach of the light emitting modules 13, here, the connecting number oflight emitting modules 13, whereby drive of the LED lighting device 11can be controlled in response to a state of the connected light emittingmodules 13.

Moreover, since the control unit 16 can, by reading in a period fromstart-up of the LED lighting device 11 up to the time T1, recognize theconnection information of the light emitting modules 13 automatically ina startup sequence before the LEDs 23 of the respective light emittingmodules 13 are lit after the LED lighting device 11 is started, that is,only by starting the LED lighting device 11, no time for recognizing theconnection information of the light emitting modules 13 is separatelyrequired, so that usability of the LED lighting device 11 is improved.

Furthermore, since the control unit 16 recognizes a current that flowsto the information output resistor 53 in a state where the voltage “a”is being applied between the main terminals 13 a and 13 b as connectioninformation of the light emitting modules 13, it becomes possible toeasily use the main terminals 13 a and 13 b of the light emitting module13 also as the information output unit 26.

Next, a fifth embodiment is shown in FIG. 8, and FIG. 8 is a graphshowing an output voltage of a constant-current power supply of anilluminating device. Also, since basic configurations of the LEDlighting device 11 are the same as those of the abovementioned fourthembodiment, these will be denoted with identical reference numerals, anddescriptions thereof will be omitted.

For the fifth embodiment, the constant-current power supply 12 is PWM(Pulse Width Modulation)-controlled. More specifically, theconstant-current power supply 12 has an ON period T2 to supply alighting voltage “b” of the LED 23 and an OFF period T3 to supply avoltage “a” lower than the lighting voltage “b” alternately, and theratio of the ON period T2 to the OFF period T3 is set as a duty ratio.Also, the LED 23 is lit even in the OFF period T3.

And, as a result of the control unit 16 recognizing a current that flowsto the information output resistor 53 due to the voltage “a” generatedin the OFF period T3 of PWM control of the constant-current power supply12 by the control unit 16, the same operations and effects as those ofthe abovementioned fourth embodiment can be provided, and it becomespossible to handle so-called hot plug, which allows for the attachmentand removal of the light emitting module 13 while the LED lightingdevice 11 is on.

Moreover, since the control unit 16 recognizes the current that flows tothe information output resistor 53 in the OFF period T3 of PWM controlof the constant-current power supply 12, that is, in a state where thevoltage “a” is being applied between the main terminals 13 a and 13 b asconnection information of the light emitting modules 13, it becomespossible to easily use the main terminals 13 a and 13 b of the lightemitting modules 13 also as the information output unit 26.

Also, in each of the abovementioned embodiments, it is possible to use,as the light source, an arbitrary light source other than the LED 23.

Moreover, the connection information that the light emitting module 13outputs from the information output unit 26 can be arbitrary informationbesides the connecting number of light emitting modules 13 and the like.

1. An illuminating device comprising: a constant-current power supplywhose output current can be variably set; a light emitting moduleincluding paired main terminals that can be connected to thisconstant-current power supply and one or more light sources connectedbetween these paired main terminals; an information output unit that isprovided in this light emitting module and that outputs connectioninformation of this light emitting module; and a control unit thatrecognizes the connection information outputted from this informationoutput unit and varies the output current of the constant-current powersupply.
 2. The illuminating device according to claim 1, wherein theinformation output unit outputs the connection information by at leasteither of the main terminals of the light emitting module.
 3. Theilluminating device according to claim 2, wherein the information outputunit includes a resistor connected between the main terminals of thelight emitting module, and the control unit recognizes a current thatflows through the resistor when a voltage given between the mainterminals by the constant-current power supply is lower than a voltageat which the light source emits light in a predetermined state as theconnection information of the light emitting module.
 4. The illuminatingdevice according to claim 3, wherein timing where the control unitrecognizes the connection information of the light emitting module is atstart-up before the light source is lit.
 5. The illuminating deviceaccording to claim 2, wherein the information output unit includes aresistor connected between the main terminals of the light emittingmodule, the constant-current power supply controls the output current byPWM control, and the control unit recognizes a current that flows to theresistor due to a voltage generated in an OFF period of the PWM controlof the constant-current power supply between the main terminals of thelight emitting module as the connection information of the lightemitting module.